Slit exposure optical system

ABSTRACT

A slit exposure optical system having a fixed original to be copied and parallelly spaced advancing photocopying paper. A lens is located between the original and photocopying paper and is associated with two reflecting mirrors to transfer an image from the original to the photocopying paper. The lens and each reflecting mirror are movable at different related speeds to maintain the optical path between the lens and the original equal to the optical path between the lens and the photocopying paper.

United States Patent lnventor Appl. No.

Filed Patented Assignee Priority Shigeru Suzuki Kanagawa-ken, Japan806,825

Mar. 13, 1969 Sept. 23, 1971 Kabushiki Kaisha Ricoh Tokyo, Japan Mar.19, 1968 Japan SLIT EXPOSURE OPTICAL SYSTEM 3 Claims, 2 Drawing Figs.

U.S. Cl 355/66, 355/ l 8 Int. Cl G03b 27/70 Field of Search 355/66, 50,51, 18

[56] References Cited FOREIGN PATENTS 455,489 1968 Switzerland 355/66Primary Examiner-Samuel S. Matthews Assistant Examiner-D. J. ClementAttorney-Burgess, Ryan and Hicks ABSTRACT: A slit exposure opticalsystem having a fixed original to be copied and parallelly spacedadvancing photocopying paper. A lens is located between the original andphotocopying paper and is associated with two reflecting mirrors totransfer an image from the original to the photocopying paper. The lensand each reflecting mirror are movable at different related speeds tomaintain the optical path between the lens and the original equal to theoptical path between the lens and the photocopying paper.

PATENTED SEP28I97I $609.03?

INVENTOR SHIGERU SUZUKI BY [l 1 M w /A v 1 Z ATTORNEYS SLIT EXPOSUREOPTICAL SYSTEM BACKGROUND OF THE INVENTION especially suited for use ina photocopying machine or the like.

Known is an optical system in which an exposure optical system, anoriginal holder and a photocopying paper supporting stand are displacedfrom one another for effecting the slit exposure upon a light-sensitivesheet material, (hereinafter referred to as photocopying paper). In caseof a photocopying machine employing such optical system of the typedescribed, a photocopying paper is transported once to an exposureposition where the paper is stopped stationarily maintaining the surfaceof the paper as planar as possible. Therefore, photocopying advancingmeans having a high degree of accuracy in operation, means formaintaining the photocopying paper in planar form and a photocopyingsupport stand having a wide area sufficient enough to cover the wholeexposure area are required. Furthermore, in a photocopying machinewherein relatively large-sized members such as the supporting stand asdescribed above must be driven, a large driving power is required andthe accurate movements of such members are extremely difficult. Thesedefects also present serious problems in making the photocopying machineor the like compact in size and simple in construction.

The primary object of the present invention is therefore to provide aslit exposure optical system which can completely eliminate such defectsas described above and serves to render the photocopying machine or thelike simple in construction, light in weight, compact in size andefficient in operation.

SUMMARY OF THE INVENTION The primary object of the present invention foreliminating the defects of the conventional slit exposure optical systemcan be attained by the slit exposure optical system of the presentinvention comprising an original holder, a slit, both of said holder andslit being held stationary, said slit being disposed adjacent to aphotocopying paper, a photocopying lens having a reflecting mirrorintegrally disposed at the rear surface of said lens, means fordirecting the lights emanating from the original upon said originalholder toward said photocopying lens and means for directing the lightsemanating from said lens toward said slit, said first and secondmentioned means and said photocopying lens being adapted to be displacedat predetermined speeds in the directions normal to and/or parallel withthe surface of the original.

According to a preferred embodiment of the present invention, said firstand second means for directing the lights emanating from the originaland said lens toward said lens and said slit respectively are comprisedof a first and a second movable reflecting mirrors disposed at 45relative to an imaginary plane containing the optical axis of saidphotocopying lens on both sides of said imaginary plane respectivelywith the intersecting lines of the reflecting surfaces of saidreflecting mirror with the imaginary plane being at right angles to theoptical axis of said lens. Both of said reflecting mirrors and saidphotocopying lens are displaced in the direction normal to and toward tothe surface of the original upon the original holder at a speed one-halfthe speed of advancing the photocopying paper while the first movablereflecting mirror and the photocopying lens are displaced along theoptical axis of the lens in the direction same with that of theadvancement of the photocopying paper at speeds the same with andonehalf said photocopying paper advancing speed. Therefore, the opticallength between the surface of the original and the photocopying lens canbe always maintained the same with the optical length between this lensto the surface of the photocopying paper. Since the speed of advancingthe photocopying paper is made equal to the speed of the first movablereflecting mirror for scanning the surface of the original, thephotocopying operation can be completely accomplished with accuracy.

The above and other objects, features and advantages of the presentinvention will become more apparent from the following description inconjunction with the accompanying drawing.

BRIEF DESCRIPTION OF DRAWING FIG. I is a sectional view of oneembodiment of a slit exposure optical system of the:present invention;and

FIG. 2 is a perspective view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, aphotocopying lens I has a reflecting mirror2'disposed in integralrelation therewith. A first reflecting mirror 3 and a second reflectingmirror 4 are disposed at 45 relative to an imaginary plane containingthe optical axis 0 of the lens 1 (a plane perpendicular to the paper inFIG. I) on both sides of this imaginary plane respectively in opposedrelation with the copying lens 1. The reflecting surfaces 30 and 4a ofthe first and second reflecting mirrors 3 and 4 are directed outwardlyof the imaginary plane. Both of the intersecting lines between theimaginary plane and the reflecting surfaces 3a and 4a of the reflectingmirrors 3 and 4, that is one side edge each of these mirrors, aredisposed at right angles to the optical axis 0 of the photocopyinglens 1. A transparent original holder 5 is disposed on the same side ofthe reflecting mirror 3 and in parallel with the imaginary plane. Upon aplane on the other side of the imaginary plane and in parallel therewithis disposed a shielding plate 7 having a slit 6 positioned in opposedrelation with the second reflecting mirror '3 An original 8 is placedupon the surface of the original holder on the opposite side thereofrelative to the reflecting mirror 3 with the image of the original beingdirected toward thereto. A photocopying paper 9 is advanced below theshielding plate 7 with the sensitized surface of the paper 9 beingdirected upwardly and toward the reflecting mirror 4. When the original8 is illuminated by the light emanating light emanating from a lightsource (not shown) disposed in the vicinity of the reflecting mirror 3,the reflected light is further reflected and made incident upon thecopying lens I where the light is focused and further reflected by thereflecting mirror 2, The reflected light from the reflecting mirror 2 isfocused upon the sensitized surface of the copying paper 9 through thereflecting mirror 4 and the slit 6 of the shielding plate 7. The copyingpaper 9 is moving at a speed of a across the slit 6 by a suitablesupporting stand (not shown) in parallel with the plate 7 so that all ofthe images of the original 8 to be copied can be focused upon thecopying paper 9 without any deviation and distortion. For this purpose,the copying lens I as well as the three reflecting mirrors are arrangedso as to displace themselves at a speed which is a function of the speeda of the copying paper 9. That is, the reflecting mirror 3, the copyinglens 1 and the reflecting mirror 4 move in the direction normal to theoriginal holder 5 at a speed of ha while the reflecting mirror 3 and thecopying lens 1 are moved in the direction of the optical axis 0 of thelens 1 at speeds ofa and ia respectively. That is, the reflecting mirror3 moves from its initial position along the line slanted at an angleof30 relative to the imaginary plane at a speedofx/5/2a; 'the lens 1,along the straight line at 45 to the imaginary plane at a speed of andthe second reflecting mirror 4, along the straight line normal to theimaginary plane at a speed of 12a toward the original holder. Theinitial positions of the copying lens 1 and the reflecting mirrors 3 and4 are determined in accordance to the direction of advance of thephotocopying paper 9. In this case, one side edge, that is the lowerside edge nearer to the copying lens I of the reflecting mirror 3 isaligned with the leading side edge of the original 8 as best shown inFIG. I. Thereafter, the positions of the copying lens I and the secondreflecting mirror 4 are determined based upon the thus determinedposition of the first reflecting mirror 3. Thus, the length of theoptical path from the copying lens I to the original 8 can be alwaysmaintained the same with the length of the optical path between theoptical lens I and the copying paper 9 so that the images of theoriginal can be all focused upon the photocopying paper 9 without anydeviation or distortion.

The intensity of light incident upon the copying paper 9 can be adjustedby means of an aperture member movably disposed on the same side withthat of the slit 6 upwardly and along the side edge thereof remote fromthe copying lens 1. The shielding plate 7 is fixed in stationaryposition so that the operation of the aperture member 10 from theexterior of the photocopying machine can be effected in a simple mannerwithout the necessity of special provision.

According to the present invention, it is possible to focus the image ofthe original held stationarily upon the surface of a moving photocopyingpaper such as rolled paper. It is therefore clear that the continuousphotocopying operation can be effected only by use of the simplephotocopying-paper-ad-v vancing mechanism such as rolled-paper-advancingmechanism, opposed to the conventional complicated paper advancingmechanism and/or stopping mechanism. Furthermore, it is necessary thatthe sensitized surface of the copying paper 9 is held in planar positiononly at one portion thereof in dimensions corresponding to the width andthe length of the slit 6 so that a large-sized copying paper supportingplate or stand is not required. Further advantage of the presentinvention is the easier exposure light adjustment without the necessityof a special mechanism because the exposure is made through a slitaccording to the present invention. Now it is clear that the features ofthe present invention are very effective to render the photocopyingmachines or the like compact in size and simple in construction withincreased photocopying efficiency.

The present invention has been so far described in detail withparticular reference to one preferred embodiment thereof, but it is tobe understood that the variations and modifications can be effectedwithout departing the true spirit of the present invention as describedhereinabove and as claimed in the appended claims.

lclaim:

l. A slit exposure optical system for use in a photocopying machinecomprising a fixed transparent holder having an original thereon to becopied;

photocopying paper spaced from said holder and adapted to be advanced ata predetermined speed relative thereto past a stationary slit to receivea reflected image from said original;

a photocopying lens having an associated mirror integrally connectedtherewith and located between said holder and said photocopying paper ina first position at the start of photocopying closer to saidphotocopying paper than said holder;

said lens having an optical axis, and said holder and said photocopyingpaper positioned in parallel relation to said axis;

a first reflecting mirror spaced from said lens and having a firstposition at the start of photocopying where said first reflecting mirroris located on one side of said axis at an angle thereto with one edgethereof in line with said axis;

a second reflecting mirror having a first position at the start ofphotocopying spaced from said first reflecting mirror on the side remotefrom said lens, said second reflecting mirror located on the other sideof said axis at an angle thereto with one edge thereof in line with saidaxis;

said lens having a second position at the termination of photocopyingprovided by being simultaneously advanced in a direction normal to saidholder at half of said predetermined speed and advanced parallel to saidholder at half of said predetermined speed to be located closer to saidholder than said photographing paper;

said first reflecting mirror having a second position at the terminationof photocopying provided by being simultaneously advanced in a directionnormal to said holder at half of said predetermined speed and advancedparallel to said holder at said predetermined speed to be located closerto said holder than said photocopying paper; and said second reflectingmirror having a second position at the termination of photocopyingprovided by being advanced in a direction normal to said holder at halfof said predetermined speed to be located closer to said holder thansaid photocopying paper.

2. A slit exposure optical system according to claim 1 in which eachsaid first and second reflecting mirrors are positioned at 45 to saidaxis, the movement of said lens from said first to said second positionis along a straight line at 45 to said axis, the movement of said firstreflecting mirror from said first to said second position is along astraight line at 30 to said axis, and the movement of said secondreflecting mirror from said first to said second position is along astraight line at to said axis.

3. A slit exposure optical system according to claim 1 in which said oneedge of said first reflecting mirror in said first position is alignedwith an edge of the original placed on said holder.

1. A slit exposure optical system for use in a photocopying machinecomprising a fixed transparent holder having an original thereon to becopied; photocopying paper spaced from said holder and adapted to beadvanced at a predetermined speed relative thereto past a stationaryslit to receive a reflected image from said original; a photocopyinglens having an associated mirror integrally connected therewith andlocated between said Holder and said photocopying paper in a firstposition at the start of photocopying closer to said photocopying paperthan said holder; said lens having an optical axis, and said holder andsaid photocopying paper positioned in parallel relation to said axis; afirst reflecting mirror spaced from said lens and having a firstposition at the start of photocopying where said first reflecting mirroris located on one side of said axis at an angle thereto with one edgethereof in line with said axis; a second reflecting mirror having afirst position at the start of photocopying spaced from said firstreflecting mirror on the side remote from said lens, said secondreflecting mirror located on the other side of said axis at an anglethereto with one edge thereof in line with said axis; said lens having asecond position at the termination of photocopying provided by beingsimultaneously advanced in a direction normal to said holder at half ofsaid predetermined speed and advanced parallel to said holder at half ofsaid predetermined speed to be located closer to said holder than saidphotographing paper; said first reflecting mirror having a secondposition at the termination of photocopying provided by beingsimultaneously advanced in a direction normal to said holder at half ofsaid predetermined speed and advanced parallel to said holder at saidpredetermined speed to be located closer to said holder than saidphotocopying paper; and said second reflecting mirror having a secondposition at the termination of photocopying provided by being advancedin a direction normal to said holder at half of said predetermined speedto be located closer to said holder than said photocopying paper.
 2. Aslit exposure optical system according to claim 1 in which each saidfirst and second reflecting mirrors are positioned at 45* to said axis,the movement of said lens from said first to said second position isalong a straight line at 45* to said axis, the movement of said firstreflecting mirror from said first to said second position is along astraight line at 30* to said axis, and the movement of said secondreflecting mirror from said first to said second position is along astraight line at 90* to said axis.
 3. A slit exposure optical systemaccording to claim 1 in which said one edge of said first reflectingmirror in said first position is aligned with an edge of the originalplaced on said holder.